Look around you in the
laboratory. Take note of the system used to store the chemicals and the
conditions and environment they are stored in. More than likely, you will
see at least one of the following examples of poor chemical storage
practices there in your laboratory :

chemicals stored in
random order

chemicals stored in
alphabetical order

chemicals stored by
poorly chosen categories, such as all acids (inorganic and organic,
strong oxidizers) together; all organics stored together

chemicals stored in hood
while hood is in use for designed purposes

flammables stored in
domestic refrigerator

food stored beside
chemicals in refrigerator

chemicals stored on
shelves above eye level

one bottle is sitting on
the top of a second bottle

overcrowded shelves
requiring manipulation of several containers to remove the container
of interest

chemicals are left on
benchtop where last used or shoved into out-of-the-way location to
make room for ongoing experiments

shelving on which
chemicals are stored is not strong enough to support chemicals or is
of inappropriate material

shelves are not securely
fastened to a permanent structure, such as wall or benchtop

shelves are not fitted
with raised lip or tilted slightly backward

inventory control is poor
or non-existent; containers are not dated; containers are obviously
ancient

some containers have no
labels or inappropriate labels which do not adequately describe the
contents or hazards

containers are stored on
the floor

caps on containers are
missing or badly deteriorated

Accidents resulting from poor
storage techniques are preventable. In most cases, the above poor storage
practices have not yet led to disaster. However, the potential for such a
disaster is extremely high. This section will provide information on
alternative storage systems which are meant to circumvent outdated storage
methods and lower the potential for an incompatible reaction. Before
discussing categorical storage arrangements, the three alternative storage
methods (random, alphabetical and incomplete categorical) will be
discussed.

Random storage - By
far the worst storage system involves no system at all, that is, random
storage. With this system, there are no restrictions to where chemicals
are stored and no limit to the number of adverse reactions that may arise
due to incompatible contacts. You may find acids next to bases, oxidizers
next to flammables, water reactives next to the sink and severe poisons
next to the writing desk. This is a laboratory waiting for a disaster to
happen.

Alphabetical storage -
Probably the most common chemical storage practice in the recent past is
that of storing chemicals in alphabetical order. When chemicals are stored
alphabetically, the situation is improved over the random storage system,
but there is still a great potential of incompatible substances coming in
physical contact, particularly during an emergency situation such as a
fire, spill or natural disaster. A wide variety of examples are possible
to illustrate the problems associated with alphabetical storage (see
Brethericks' Handbook of Reactive Chemical Hazards, or NFPA 491M : Manual
of Hazardous Chemical Reactions) that may be encountered, and the danger
associated with the chance encounter. The following list provides numerous
of these examples.

Problems with Alphabetical Chemical Storage

Acetic acid + acetaldehyde
small amounts of acetic acid will cause the acetaldehyde to
polymerize, releasing large amounts heat

Incomplete or Poorly
Chosen Categorical StorageThis system provides some differentiation between hazard classes of
chemicals, and as such is an improvement over the alphabetical storage
policy. Examples of how chemicals may be divided are listed below.

acids are stored
separately, but nitric and perchloric acid are not isolated and
perhaps the perchloric acid is stored on wooden (combustible) shelves

solids are stored
separately from liquids, but flammable solids are stored next to solid
oxidizers

organics are separated
from inorganics, but flammables and extreme toxics are not segregated
from the less hazardous materials

no provision is made for
water reactives, either liquids or solids

Any of these categorical
attempts at segregating hazard classes is better than no separation at
all, and the resulting potential for dangerous contact between
incompatible substances has been greatly decreased. However, undesirable
contacts are still possible and more complete classification needs to be
done. This is accomplished through a complete categorical storage system.